It has been well known to provide plastic wear members for railway vehicles. For example, U.S. Pat. Nos. 4,188,888; 4,237,792 and 4,289,077 show wear members in the form of liners for center bearings of trucks. Wear members of plastic have also been widely used at the sliding surfaces of coupler members, as disclosed in U.S. Pat. Nos. 4,238,039; 4,249,665; 4,261,472, and 4,264,015. Plastic wear members have further been used for pedestals of a railway truck, as disclosed in U.S. Pat. Nos. 4,237,793 and 4,239,007.
Heretofore, it has also been known to provide wear members for brake rods. One well known wear member is in the form of a plastic sleeve fittable over the brake rod and held in place by a metal retainer, as disclosed in U.S. Pat. No. 4,079,818. The entire wear member is of plastic material and merely fits over the brake rod so as to define a plastic surface for engagement with a U-shaped hanger and for the primary purpose of protecting the brake rod and support hanger from wear in the area where the rod is supported. This wear member is not readily usable for repairing a worn brake rod.
Another wear member for a brake rod is disclosed in U.S. Pat. No. 4,452,345, which is in the form of a plate of plastic material that is attached to a U-shaped hanger to provide a plastic surface on which the brake rod is slidably supported. This wear device likewise cannot be used to repair a worn brake rod.
These wear members have been developed following the availability of suitable plastic resins and particularly certain polyethylenes, such as a linear high-density polyethylene which is usually referred to as an ultra-high molecular weight polyethylene. As disclosed in some of the above patents, these plastic materials have been bonded to metal supporting members which are then mounted on supporting parts of a railway vehicle.